Add support for POWER8 (and maybe earlier) CPUs. Not sure if this works on

real hardware, but it gets the kernel booting on QEMU emulating a POWER8
CPU so it's a step in the right direction.

This establishes a way to distinguish CPU features based on the AT_HWCAP
and AT_HWCAP2 features documented in the ELF ABI.  Also use this to
determine the availability of the DARN instruction instead of keying of
the processor model.

5 files changed, 64 insertions, 24 deletions

diff --git a/sys/arch/powerpc64/include/cpu.h b/sys/arch/powerpc64/include/cpu.h
index bc01c1fe6a5..2c716378f66 100644
--- a/sys/arch/powerpc64/include/cpu.h
+++ b/sys/arch/powerpc64/include/cpu.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.h,v 1.23 2020/07/23 16:21:44 kettenis Exp $	*/
+/*	$OpenBSD: cpu.h,v 1.24 2020/08/23 10:07:51 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -160,6 +160,15 @@ void	cpu_startclock(void);
 
 #define curpcb			curcpu()->ci_curpcb
 
+extern uint32_t cpu_features;
+extern uint32_t cpu_features2;
+
+#define PPC_FEATURE2_ARCH_3_00	0x00800000
+#define PPC_FEATURE2_DARN	0x00200000
+
+void cpu_init_features(void);
+void cpu_init(void);
+
 static inline unsigned int
 cpu_rnd_messybits(void)
 {
diff --git a/sys/arch/powerpc64/include/cpufunc.h b/sys/arch/powerpc64/include/cpufunc.h
index e9228587f3e..d6c2cbd31d0 100644
--- a/sys/arch/powerpc64/include/cpufunc.h
+++ b/sys/arch/powerpc64/include/cpufunc.h
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpufunc.h,v 1.7 2020/07/10 23:22:48 gkoehler Exp $	*/
+/*	$OpenBSD: cpufunc.h,v 1.8 2020/08/23 10:07:51 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -131,6 +131,12 @@ mtdec(uint32_t value)
 	__asm volatile ("mtdec %0" :: "r"(value));
 }
 
+static inline void
+mtsdr1(uint64_t value)
+{
+	__asm volatile ("mtsdr1 %0" :: "r"(value));
+}
+
 static inline uint32_t
 mfpvr(void)
 {
@@ -153,6 +159,9 @@ mtlpcr(uint64_t value)
 	__asm volatile ("mtspr 318, %0" :: "r"(value));
 }
 
+#define LPCR_LPES	0x0000000000000008UL
+#define LPCR_HVICE	0x0000000000000002UL
+
 static inline void
 mtptcr(uint64_t value)
 {
diff --git a/sys/arch/powerpc64/powerpc64/cpu.c b/sys/arch/powerpc64/powerpc64/cpu.c
index 43a1b8ed98f..38b53fb6668 100644
--- a/sys/arch/powerpc64/powerpc64/cpu.c
+++ b/sys/arch/powerpc64/powerpc64/cpu.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: cpu.c,v 1.16 2020/08/14 12:13:01 kettenis Exp $	*/
+/*	$OpenBSD: cpu.c,v 1.17 2020/08/23 10:07:51 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -56,6 +56,9 @@ struct cpu_version cpu_version[] = {
 };
 
 char cpu_model[64];
+uint32_t cpu_features;
+uint32_t cpu_features2;
+
 uint64_t tb_freq = 512000000;	/* POWER8, POWER9 */
 
 struct cpu_info cpu_info[MAXCPUS];
@@ -175,13 +178,9 @@ cpu_attach(struct device *parent, struct device *dev, void *aux)
 		level++;
 	}
 
-	if (CPU_IS_PRIMARY(ci)) {
-		switch (CPU_VERSION(pvr)) {
-		case CPU_IBMPOWER9:
-			timeout_set(&cpu_darn_to, cpu_darn, NULL);
-			cpu_darn(NULL);
-			break;
-		}
+	if (CPU_IS_PRIMARY(ci) && (cpu_features2 & PPC_FEATURE2_DARN)) {
+		timeout_set(&cpu_darn_to, cpu_darn, NULL);
+		cpu_darn(NULL);
 	}
 
 #ifdef MULTIPROCESSOR
@@ -216,6 +215,31 @@ cpu_attach(struct device *parent, struct device *dev, void *aux)
 }
 
 void
+cpu_init_features(void)
+{
+	uint32_t pvr = mfpvr();
+
+	switch (CPU_VERSION(pvr)) {
+	case CPU_IBMPOWER9:
+		cpu_features2 |= PPC_FEATURE2_ARCH_3_00;
+		cpu_features2 |= PPC_FEATURE2_DARN;
+		break;
+	}
+}
+
+void
+cpu_init(void)
+{
+	uint64_t lpcr = LPCR_LPES;
+
+	if (cpu_features2 & PPC_FEATURE2_ARCH_3_00)
+		lpcr |= LPCR_HVICE;
+
+	mtlpcr(lpcr);
+	isync();
+}
+
+void
 cpu_darn(void *arg)
 {
 	uint64_t value;
@@ -252,11 +276,7 @@ cpu_bootstrap(void)
 	msr = mfmsr();
 	mtmsr(msr | (PSL_ME|PSL_RI));
 
-#define LPCR_LPES	0x0000000000000008UL
-#define LPCR_HVICE	0x0000000000000002UL
-
-	mtlpcr(LPCR_LPES | LPCR_HVICE);
-	isync();
+	cpu_init();
 
 	pmap_bootstrap_cpu();
 
diff --git a/sys/arch/powerpc64/powerpc64/machdep.c b/sys/arch/powerpc64/powerpc64/machdep.c
index 2f36148c222..96e36a550c1 100644
--- a/sys/arch/powerpc64/powerpc64/machdep.c
+++ b/sys/arch/powerpc64/powerpc64/machdep.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: machdep.c,v 1.56 2020/08/17 16:55:41 kettenis Exp $	*/
+/*	$OpenBSD: machdep.c,v 1.57 2020/08/23 10:07:51 kettenis Exp $	*/
 
 /*
  * Copyright (c) 2020 Mark Kettenis <kettenis@openbsd.org>
@@ -171,11 +171,8 @@ init_powernv(void *fdt, void *tocbase)
 	msr = mfmsr();
 	mtmsr(msr | (PSL_ME|PSL_RI));
 
-#define LPCR_LPES	0x0000000000000008UL
-#define LPCR_HVICE	0x0000000000000002UL
-
-	mtlpcr(LPCR_LPES | LPCR_HVICE);
-	isync();
+	cpu_init_features();
+	cpu_init();
 
 	/* Add all memory. */
 	node = fdt_find_node("/");
diff --git a/sys/arch/powerpc64/powerpc64/pmap.c b/sys/arch/powerpc64/powerpc64/pmap.c
index 4c69b41d163..6dfee10cace 100644
--- a/sys/arch/powerpc64/powerpc64/pmap.c
+++ b/sys/arch/powerpc64/powerpc64/pmap.c
@@ -1,4 +1,4 @@
-/*	$OpenBSD: pmap.c,v 1.42 2020/08/21 13:42:02 kettenis Exp $ */
+/*	$OpenBSD: pmap.c,v 1.43 2020/08/23 10:07:51 kettenis Exp $ */
 
 /*
  * Copyright (c) 2015 Martin Pieuchot
@@ -1451,8 +1451,13 @@ pmap_bootstrap_cpu(void)
 	/* Clear TLB. */
 	tlbia();
 
-	/* Set partition table. */
-	mtptcr((paddr_t)pmap_pat | PATSIZE);
+	if (cpu_features2 & PPC_FEATURE2_ARCH_3_00) {
+		/* Set partition table. */
+		mtptcr((paddr_t)pmap_pat | PATSIZE);
+	} else {
+		/* Set page table. */
+		mtsdr1((paddr_t)pmap_ptable | HTABSIZE);
+	}
 
 	/* Load SLB. */
 	for (idx = 0; idx < 31; idx++) {